Aqueous Oil Emulsions Research Articles

Enhancing the biodesulphurization capacity of Rhodococcus sp. FUM94 in a biphasic system through optimization of operational factors

The biodesulfurization activity of bacteria through the 4S pathway in aqueous-oil emulsions is affected by various operational factors. These factors also demonstrate interacting effects that influence the potential for field applications of biodesulfurization technology and can solely be deciphered through multi-variable experiments. In this study, the effects of the influential factors and their interactions on the desulfurizing activity of a newly identified desulfurizing bacterium, Rhodococcus sp, FUM94 were quantitatively investigated. The capacity improvement achieved through optimized values obtained in this study is significant due to its simple implementation to large scale processes. This is the most simple and the most cost-effective way to scale-up a biodesulfurization process.Using response surface methodology (RSM). Optimum values of the factors were identified with the objective of maximizing biodesulfurization activity. Results revealed that the desulfurization activity of the biocatalyst increased from 0.323 ± 0.072 to 46.57 ± 4.556 mmol 2-Hydroxybiphenyl (kg dry cell weight)-1 h-1 at the optimized conditions of 6 h reaction time, 2 g.L-1 biocatalyst concentration, 0.54 mM (100 ppm) dibenzothiophene (DBT) concentration (sulfur source), and 25% oil phase fraction. Desirability analysis proved that the selected conditions are the most desirable combination of factors (desirability value = 0.896) to achieve the highest biodesulfurization activity of the biocatalyst. A comparison between the biodesulfurization capacity achieved in this study and the capacities reported in similar studies published in the past two decades revealed that biodesulfurization under optimized operational conditions outperforms previously proposed techniques.

Oviposition responses of Queensland fruit fly (Bactrocera tryoni) to mineral oil deposits on tomato fruit

AbstractBehavioural responses of wild and laboratory‐culture females of Queensland fruit fly, Bactrocera tryoni (Froggatt) (Diptera: Tephritidae), to mineral oil deposits on tomato fruit dipped in aqueous oil emulsions were assessed in a no‐choice test and three choice tests. The oils were two commercial products used to manage plant pests and diseases, Ampol D‐C‐Tron NR and SK EnSpray 99, one distillation fraction of the base oil of the former, and four distillation fractions of the base oil of the latter. The initial and final boiling points of the fractions were equivalent to those of n‐alkanes with chain lengths of C20–22 (Ampol), and C21–C23, C22–23.5, C22–24, and C22–24.5 (SK). For both fly types in the no‐choice test, numbers of punctures and eggs per fruit declined strongly as concentrations of the nC20–22 Ampol fraction in emulsions rose from 0.25 to 2% (vol/vol). Fly type affected the extent of responses but there was no significant interaction for fly type*oil concentration. Responses of laboratory‐culture females in the choice tests also declined as concentrations of SK and the four fractions of its base oil in emulsions rose from 0 to 0.25%. The SK nC22–24 and nC22–24.5 fractions had least impact. Responses of laboratory‐culture flies to 0.5% emulsions of the nC20–22 Ampol fraction and the nC21–23 SK fraction in choice tests were not significantly different. Likewise, responses of laboratory‐culture flies to 0.5% emulsions of the two commercial products were not significantly different. Emulsifier type did not affect numbers of punctures or eggs per fruit in choice responses of laboratory‐culture flies to 0.5% emulsions of the Ampol nC20–22 fraction or 0.5% emulsions of the SK nC21–23 fraction. If the equivalence of no‐choice and choice responses in the laboratory were to hold in the field, then unsprayed ‘sacrificial’ plants would not be necessary and oil emulsions could be used as cover sprays.

Modified PTFE–PANI membranes for the recovery of oil products from aqueous oil emulsions

Composite membranes have been prepared by modifying a polytetrafluoroethylene membrane with aniline hydrochloride, and the effect of polymerization time on the efficiency of the recovery of petroleum products from aqueous oil emulsions was studied. It has been found that the modification leads to an increase in the degree of oil removal from oil-in-water emulsions by 29%. The specific productivity of the original and modified membranes has been determined with distilled water and water–oil emulsions. It has been found that the specific productivity of the membranes decreases with the time of membrane treatment with ammonium persulfate. The surface of the modified membranes has been studied with the aid of a scanning electron microscope, and the elemental composition of composite membrane surfaces has been examined by X-ray fluorescence analysis. It has been determined that the modification of a polytetrafluoroethylene membrane with aniline hydrochloride leads to an increase in the carbon content and the appearance of nitrogen, oxygen, and sulfur atoms.

A three-dimensional spheroidal cancer model based on PEG-fibrinogen hydrogel microspheres.

Three-dimensional (3D) invitro cancer models offer an attractive approach towards the investigation of tumorigenic phenomena and other cancer studies by providing dimensional context and higher degree of physiological relevance than that offered by conventional two-dimensional (2D) models. The multicellular tumor spheroid model, formed by cell aggregation, is considered to be the "gold standard" for 3D cancer models, due to its ease and simplicity of use. Although better than 2D models, tumor spheroids are unable to replicate key features of the native tumor microenvironment, particularly due to a lack of surrounding extracellular matrix components and heterogeneity in shape, size and aggregate forming tendencies. In order to address this issue, we have developed a 3D "tumor microsphere" model, formed by a dual-photoinitiator, aqueous-oil emulsion technique, for the encapsulation of cancer cells within PEG-fibrinogen hydrogel microspheres and for subsequent long-term 3D culture. In comparison to self-aggregated tumor spheroids, the tumor microspheres displayed a higher degree of size and shape homogeneity throughout long-term culture. In sharp contrast to cells in tumor spheroids, cells within tumor microspheres demonstrated significant loss in apico-basal polarity and cellular architecture, cellular and nuclear atypia, increased disorganization, elevated nuclear cytoplasmic ratio and nuclear volume density and reduction in cell-cell junction length, all of which are hallmarks of malignant transformation and tumorigenic progression. Additionally, the tumor microsphere model was extended for the 3D encapsulation and maintenance of a wide range of other cancer cell (metastatic and non-metastatic) types. Taken together, our results reinforce the importance of incorporating a biomimetic matrix in the cellular microenvironment of 3D tumor models and the influential effects of the matrix on the tumorigenic morphology of 3D cultured cells. The tumor microsphere system established in this study has the potential to be used in future investigations of 3D cancer cell-cell and cell-ECM interactions and in drug-testing applications.

Continuous production of biodiesel using whole-cell biocatalysts: Sequential conversion of an aqueous oil emulsion into anhydrous product

A continuous production of biodiesel from an aqueous plant oil emulsion was attempted using immobilized fungal whole cells. Six packed-bed reactors were connected in series and operated with stepwise methanol addition. In the first column, more than 3% water was necessary for methanolysis to proceed. Despite the low initial water content of 0.36%, the methyl ester content in the effluent from the second column increased similarly in a wide range of contents of water (0–20%) added, which shows the water-content-independent reaction in this column in contrast to the reaction in the first column. Further investigations using reaction mixture models suggested a contribution of the composition of the reaction mixture to the phenomenon. On the basis of these findings, the sequential methanolysis through six columns was attempted, where the upper layer of the effluent from each column was supplied into the next column without further addition of water. Consequently, an aqueous plant oil emulsion with 3% water was converted into the final product with 96.1% methyl ester and 0.15% water. Therefore, the system developed is useful for producing biodiesel enzymatically from water-containing feedstocks.

Bacterial Microflora of Contaminated Metalworking Fluids

ABSTRACTMetal working fluids (MWF) are commonly used in manufacturing and machining industries. There are four major classes of MWF: (i) which contain lubricant base oils without water (straight oils), (ii) composed of an aqueous oil emulsion with oil in high concentration (soluble oils) or (iii) lower concentration (semi-synthetic MWF) and (iv)formulated with no petroleum oils (synthetic fluid). Historically, microbial contamination of metal working fluids has been a problem in the metalworking industries, primarily because of potential adverse health effects and microbial growth effects on fluid quality and performance. Metalworking fluids are chemically complex mixtures. Such mixtures render MWFs potentially toxic to the environment. One solution to the disposal problem is on-site biological treatment of waste MWFs, using bioreactor systems. Bioaugmentation with selected strains may improve the opportunity to create more reproducible system.In this study the bacterial microflora of soluble oil and synthetic metalworking fluid in-use was quantified, isolated and tentatively identified. An indicator plates for dehydrogenase activity were used in attempt to demonstrate the potential of bacteria isolated from contaminated metalworking fluids to utilize hydrocarbons—a component of MWFs.

Investigations And Field Observations On The Occurrence Of Flashing Phenomena During Sucker-Rod Pumping Of Hot Fluids From Thermal Processes

Abstract Flashing of high-temperature, near-saturation, aqueous oil emulsions and inflow of steam and volatiles produced during the thermo-recovery process of heavy oil are decreasing the efficiency of conventional sucker-rod pumping systems. This paper describes novel laboratory methods aiming to allow direct observations of this phenomena and assess the rationale and effectiveness of external speed control and better valve design to improve pumping efficiency. A 1:1 operational replica of a sucker-rod pump in which the pump barrel and valve cages have been constructed from Plexiglas, was used for laboratory simulations and room temperature visualization of effects induced by gas inflow and vapor flashing. Mixtures of Freon 114 and oil were used to simulate at room temperature flashing of high-temperature, high-pressure fluids, and a laser Doppler anemometer was used to measure the velocity within the pump. The presence of gas, either from inflow or by generation of vapor flashing resulted in a decrease of the pump efficiency. Visual observation of the occurrence of flashing within the pump could be directly related to regions of critical velocity peaks. The design of valves studied created image dimensional velocity fields with areas of high velocity reversing and stagnant flows, resulting in the flashing occurring at uneven intensities within the valve. The experimental rig and investigative methods developed offer a tool to assess pump operating strategies and designs for improving the pumping efficiency during adverse thermo-recovery conditions. Introduction The processes used for the recovery of hydrocarbons from oil sand and heavy oil reservoirs often results in the production of hot multiphase fluids. The current downhole artificial lift systems, which have been transferred from conventional operations, are not well adapted to pumping thermal, near saturation fluids. In certain situations a mixture of liquid oil emulsions, steam and non-condensable organic volatiles enters the pump and, as a result of local pressure and velocity distributions in the pump chambers and their oscillatory variation during the stroke, flashing of hot fluids occur. These situations can decrease the efficiency of a standard sucker-rod pumping system and can often lead to vapor lock and fluid pound conditions, equipment damage and drop of production rates. Additionally, production fluids are frequently laden with considerable solids that can cause costly shutdowns and well workovers. To improve the pumping process, a great need exists for assessing and understanding the effect of local velocity distributions to irreversible phase-change and solid-liquid-gas phase phenomena. New investigations methods are first assessed and then used for testing rationale equipment modifications and suitable operating strategies. This paper describes and assesses novel experimental apparatus aiming to allow direct observations and measurements of multiphase transport during the pumping process. The apparatus consists of a 1:1 operational sucker-rod pump in which the barrel and cages are made of Plexiglas allowing direct visualization of the flow within the pump. The following experimental procedures are assessed in a preliminary experimental program:—use of a laser Doppler anemometer to measure the velocity field within the pump,—use of a Freon-oil mixture to simulate high-temperature, high-pressure fluids and produce flashing induced perturbations at room temperature.

Generation of polyunsaturated fatty acids from vegetable oils using the lipase from ground oat (Avena sativa L.) seeds as A Catalyst

Ground oat seeds can serve as a source of lipase in both aqueous-oil emulsions and in organic solvents. In organic solvents the lipase lost selectivity for monounsaturated fatty acids. Because of this, polyunsaturated vegetable oils were rapidly split. The lipase source is very inexpensive and is recyclable, to a certain extent.

Headspace gas chromatographic determination of aromatic hydrocarbons in natural and waste water

The possibilities of using headspace analysis of aromatic hydrocarbon traces in aqueous solutions with changing values of the partition coefficients are discussed. A variant of headspace analysis of the simplest aromatic hydrocarbon in natural and waste water is described. It involves two-step gaseous extraction of a sample in vessels of varying volume before and after the equilibrium phase is replaced with a pure gas (air or nitrogen). This method permits to analyse 5–50 ml water samples with benzene and toluene contents varying from the ppb to the ppm range within an error not exceeding 155. The analysis time is about 1.5 h. The presence of non-volatile organic or mineral substances does not influence the determination. This method is unsuitable to heterogeneous systems (aqueous oil emulsions): before carrying out the analysis for the hydrocarbon content these systems have to be homogenized first.

Corrosion Fatigue Behaviour of Armco‐Iron as a function of heat treatments

AbstractA corrosion fatigue testing device is presented which satisfies in a simple way many needs of this kind of research. In particular, the behaviour of stresses and strains vs. time is known at every point of the specimen; load may be varied and controlled; electrochemical measures are easily obtained; reproducibility is assured. The specimen acts as a cantilever beam. Results are presented and discussed concerning alterations in the structure of Armco iron as a consequence of the following two heat treatments: A. heating in a vacuum furnace at 760°C for two hours, quenching in water (some experiments have been performed quenching in NaCl solution or in aqueous oil emulsion) at 20 °C. B. heating in a vacuum furnace at 760°C for one hour, then at 925°C for four hours, quenching under the same conditions as in A. Sensitization and protection with respect to intergranular attack and consequently to the rate of fatigue corrosion cracking respectively follow the two above mentioned heat treatments.